Introduction: In the Pediatric Intensive Care Unit (PICU), maintaining stable cerebral blood flow (CBF) is essential incirtically ill children, as fluctuations can lead to severe neurological complications. Cerebral autoregulation (CA) ensures stable CBF despite changes in systemic blood pressure. Traditional methods such as intracranial pressure (ICP) monitoring and transcranial Doppler (TCD) provide indirect assessments of CA and are often invasive or limited in continuous monitoring. Near-infrared spectroscopy (NIRS) offers a more non-invasive alternative by continuously measuring cerebral oxygenation. By correlating cerebral regional oxygen saturation (CrSO2) with, though invasive, mean arterial pressure (MAP), the cerebral oximetry index (COx) can be calculated, quantifying the brain’s autoregulatory efficiency. This allows clinicians to determine the optimal MAP (MAPopt) per individual, where CA is most effective, which could improve patient outcomes by maintaining stable cerebral perfusion.
Objective: This thesis aims to evaluate COx, derived from (CrSO2) and MAP, to identify the MAPopt in pediatric patients undergoing surgery for congenital diaphragmatic hernia (CDH) or esophageal atresia (EA). Additionally, it examines differences in CA across pre-, intra-, and postoperative phases, providing insights into how surgery affects CA.
Method: Left and right CrSO2 and MAP signals, pre-, intra-, and post-operatively, were retrospectively analyzed to assess CA using the COx. Data preprocessing involved the removal of artifacts, normalization, and signal alignment. COx was calculated as the moving Pearson correlation of CrSO2 with MAP over time
using a 5 minute sliding window with a one minute stepsize. Impaired CA was defined as a COx cut-off value ≥ 0.3, defining a correlation between the MAP and CrSO2. The MAPopt was identified as the MAP associated with the lowest COx values, representing the most effective CA. The optimal MAP range was calculated per patient.
Results: CA was interpreted to be most compromised during the intraoperative phase, with elevated COx values in both CDH and EA patient groups. The MAPopt was successfully determined in most cases, showing variability across operative states, with lower values observed intraoperatively. The percentage of time with COx above the cut-off of 0.3 was highest during surgery, especially for EA patients. No remarkable differences were found between the left and right CrSO2 signals.
Conclusion: The study demonstrates the feasibility of using NIRS-derived COx to determine MAPopt in neonates undergoing CDH or EA surgery. These findings highlight the potential for individualized MAP targets
to optimize cerebral perfusion, especially during critical surgical interventions.